In storage (recording) devices used for data and information systems, semiconductor memories and magnetic memories are generally used for data storage. For applications specifying short access times, semiconductor memories are generally used in internal storage devices. For applications specifying huge capacity and non-volatility, hard disk drives (HDDs) are generally used which employ magnetic disks as external storage devices. Storage capacity is an important index to indicate the capability of magnetic disk devices. Magnetic disk devices with huge capacity and having compact size have been increasingly requested by the market with recent developments of the information age.
The volume of information processing in the information age is increasing rapidly. In particular, HDDs, which are external storage devices, have been desired to store more information in its limited area and volume. A technical approach to this desire is to increase the capacity by increasing the recording density of the HDD. To achieve higher recording density, further miniaturization of recording bits is effective. Hence, in this approach, the size of a particle which is the unit of recording in a medium has been reduced.
The further miniaturization, however, reduces the thermal stability of a recording bit which can cause evanescence of magnetic information over time by thermal fluctuations so that the non-volatility of magnetic information becomes unsatisfactory. Accordingly, to ensure thermal stability of the HDD, recording media with higher coervicity are chosen. However, it has generally been known that recording media with high coervicity are difficult to record data to. In magnetic recording, the recording magnetic field from a recording head is generally stronger than the coervicity of the medium and is changed abruptly. The production of a high recording magnetic field in a highly microscopic area is extremely difficult to obtain.
Therefore, a magnetic recording method and disk drive which can overcome these problems associated with disk drives generally used would be very desirable.